Re: [PATCH] 2.4.19 do_adjtimex parameter checking

[Ulrich Windl]

On 21 Mar 2002, at 8:40, Paul Gortmaker wrote to me:

> Spotted by Tajthy.Tamas @ datentechnik.hu:
> 
> Adjtimex modes may contain other bits set in addition to
> ADJ_OFFSET_SINGLESHOT bits, and hence tests for strict (in)equality
> are not appropriate - must test for ADJ_OFFSET_SINGLESHOT
> bits set in modes.  Three places in the code where this test
> is made - oddly enough the 3rd is already correct.

Hello, 
masters of the bits,

basically no: adjtimex() is either adjtime() or ntp_adjtime or 
ntp_gettime(). While one could think to set multiple bit combinations, 
it was never intended. At the user level adjtimex() should never have 
existed. This patch would open a new incompatible use of adjtimex() by 
blessing what was illegal before IMHO.

ADJ_OFFSET_SINGLESHOT has be be used alone, specifically also to return 
the correct return value.

Regards,
Ulrich

> 
> 
> --- linux/kernel/time.c~	Thu Feb 28 09:37:32 2002
> +++ linux/kernel/time.c		Thu Mar 21 08:27:49 2002
> @@ -216,7 +216,7 @@
>  		
>  	/* Now we validate the data before disabling interrupts */
>  
> -	if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
> +	if (((txc->modes & ADJ_OFFSET_SINGLESHOT) != ADJ_OFFSET_SINGLESHOT) && (txc->modes & ADJ_OFFSET))
>  	  /* adjustment Offset limited to +- .512 seconds */
>  		if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
>  			return -EINVAL;	
> @@ -275,7 +275,7 @@
>  	    }
>  
>  	    if (txc->modes & ADJ_OFFSET) {	/* values checked earlier */
> -		if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
> +		if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) {
>  		    /* adjtime() is independent from ntp_adjtime() */
>  		    time_adjust = txc->offset;
>  		}
> 
>